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There are a few reasons for grinding into the edge before you start, the main reason I started doing it was that the steel is weakened beyond the actual damage due to dulling, if this isn't ground off before the edge is sharpened then the edge will form in this weakened area.

This can be seen on a macroscopic level if you just bend a piece of steel back and forth until it breaks and look at the steel in the area adjacent to the break and you will see the obvious stress lines. The same can be seen of course in regards to cracks, the steel is damaged beyond the immediate chips/fractures.

How much of it you have to do, and how much of an effect it makes depends of course on how the knife was used. It may be only a very light pass is needed, or it may be 3-5 passes are needed. It is easy to see visually because the light reflection will even out.

Chris has noted another reason to do it and there are others such as it prevents uneven wear in the edge, formation of recurves, etc. .

It will also have a large affect on how the edge forms as it will be very obvious when the edge is forming in clean steel because the edge will form to the scratch pattern and the burr (deformation/fracture) is minimal.

There is a detailed discussion on this on the Wicked Edge forum now for anyone interested in more details.

As an aside, "Cliff Stamp", isn't a screen name, it is my actual name.

Adam Marr

Post subject: Re: Starting a new edge?

Posted: Fri Feb 14, 2014 7:23 pm

Forum Moderator

Joined: Mon Apr 23, 2012 7:36 pmPosts: 3284

Moderator Note:

This thread will be left open, at least by me, for so long as it remains ENTIRELY civil by all parties.

The slightest sniff/hint of trouble and it will be locked and those involved in any indiscretion will be warned and possibly asked to leave the forum.

This is a good teachable moment here. I want to remind our forum members to please refrain from disparaging remarks about other people, competitors etc on this forum. I'm sure I haven't always lived up to this standard 100% but really, let's try to be respectful and keep it congenial. We're talking about kitchen knives and sharpening so there is no real need to get personal.

Certainly one needs to get down to good metal one way or the other. Its all personal preference / time restraints / available tools as far as the technique used to accomplish that. Nothing wrong with any method as long as it works for you and the end result is satisfactory.

_________________Pete in San Ramon

Cliff Stamp

Post subject: Re: Starting a new edge?

Posted: Fri Feb 14, 2014 8:34 pm

Joined: Fri Feb 14, 2014 4:23 pmPosts: 7

pjwoolw wrote:Certainly one needs to get down to good metal one way or the other.

As with most techniques, as you said it depends on the person's goals. For example a smooth steel certainly does not destress the edge, it has to do the opposite (as the only material removal is by adhesion) but yet they are very popular - why, because they are fast and simple. If you do not care about having the sharpest edge, or the best edge retention/durability, but just want to keep a blade cutting with minimal investment - then smooth steels, or even the dreaded butchers steel can work well.

It just gets off when you do odd combinations. For example get a very nice knife with a very high end steel with a very demanding thermal processing, and then maintain that edge with a smooth steel (how about a 64 HRC flash soak, oil quench, triple deep quench AEB-L chef's knife 0.001":5dps/10 dps micro) . In that case a lot of the potential of the steel in the knife is never being seen which is why in general if people prefer using smooth steels to sharpen I would recommend they stay with simple steels for knives.

Can you use them on really nice blades, sure, but the edge is always stressed and why did you pay all that money to get the steel in an ultra-high performance state if you are always going to use it heavy fatigued? It is like getting a very UHC white steel and then keeping the edge finished at 20 dps with a 600 grit DMT. That steel has a lot of potential being wasted and a more coarse HC steel would actually have superior performance at that angle/finish.

As with most things I would recommend you try it, I have never had anyone do it and then complain about it to me and in fact people who do often respond with very strong positive comments, again as noted just look at the WE thread where a few people have picked it up and tried it. However, as with most feedback type arguments there is a strong potential for bias because if it didn't work there is a chance the individual would never tell me but a lot of people who have success will want to thank the guy that helped them.

pjwoolw wrote:As with most techniques, as you said it depends on the person's goals. For example a smooth steel certainly does not destress the edge, it has to do the opposite (as the only material removal is by adhesion) but yet they are very popular - why, because they are fast and simple. If you do not care about having the sharpest edge, or the best edge retention/durability, but just want to keep a blade cutting with minimal investment - then smooth steels, or even the dreaded butchers steel can work well.

I would stress that most people using a steel or rod are not doing this to replace a true or full sharpening. Steels and rods are most commonly used in situations where an edge needs improvement but there is not time or proper situation for a full sharpening. They are used to get by until there is time to sharpen.

_________________If at first you don't succeed, pay someone that knows what they're doing.

taz575

Post subject: Re: Starting a new edge?

Posted: Sat Feb 15, 2014 7:19 am

Forum Moderator

Joined: Thu Apr 26, 2012 5:13 pmPosts: 3098Location: CT

Weakened metal does need to be removed. Some like to run the edge on the stone, which is good to prevent dips in the edge like was mentioned (prevent getting recurved edges, making sure the edge profile is where it should be, etc). Different steels will weaken at different rates, hardness, thickness, useage all play into this. Do you need to remove steel each time you touch up/strop? Not usually. Each time you fully sharpen, possibly, depending on a variety of factors. If I need to tweak the edge profile or do thinning, I will run against the stone to start. Normal sharpening w/o dropping down to a 500 stone (or lower), I will form a burr with a 1K stone or Aoto, remove the burr and then start sharpening trying to keep a minimal burr as I progress up in grits. I usually strop on the fuzzy side of leather between each stone to remove any burr. I will deburr after my highest grit stone with leather, and then touch up with a tiny micro bevel on the highest grit stone, usually stropping with very light pressure. Sometimes stropping just aligns the burr, but doesn't fully remove it, so I run the edge thru cork or strop on the stones to fully remove the burr. I can feel the difference in the edge itself when it's a true sharp edge or if there is a tiny burr left.

When I regrind/thin knives, I try to keep the edge from going to a zero edge. This weakens the edge a good bit and leaves a tin foil like edge that just crumbles. This can also happen if you use a belt sander to sharpen to the final edge; it will be very weak and thin and crumbly. Buffing to remove the burr helps, but usually leaves the edge rougher from the burr breaking off and not a true edge. If there is an edge bevel on the knife already when I am thinning it, I try to turn the edge bevel into a micro bevel, but not completely remove it. If I do, I flatten the edge since I know the steel there has been weakened by the grinding and flexing back and forth. Even thinning on stones, you can weaken the edge. I know we all want thin behind the edge knives, but there is a limit!

Cliff Stamp

Post subject: Re: Starting a new edge?

Posted: Sat Feb 15, 2014 4:07 pm

Joined: Fri Feb 14, 2014 4:23 pmPosts: 7

taz575 wrote:I will form a burr with ...

If you are burr sharpening then it isn't as useful primarily to reset the edge before you sharpen in regards to getting to quality metal because you are going to intentionally over sharpen the edge anyway which in many cases will remove damaged metal as you are going beyond the blunted point. If you are burr sharpening then edge resets are generally only required for stability reasons on heavier use knives which take impacts. In that case how the burr forms can often tell you if enough metal was removed in the reset.

Resetting the edge however removes the need for burr sharpening as you can tell by eye visually when the apex is < 20 microns thick (most people stop being able to see the light reflecting at this point). With no requirement to form a burr this removes all burr removal techniques, many of which are actually stressful on the edge, such as smashing it back into the edge to attempt to break it off. Steel never breaks clean, and again the damage to the steel will be deeper than the break.

Of course you don't need an edge reset to not burr sharpen, you can just check the edge for sharpness, but the visual check is very quick and it is location specific which also points out the grind symmetry and on new knives this can be critical to understand why some parts of the edge are responding and some parts are not.

A lot of this is also very steel specific. For example I have a lot of knives in very high edge stability steels which take very little damage in use. AEB-L, O1, 1095 etc. will all take very low angles and do a lot of cutting, even going down to fairly dull (< 5% of optimal) and still the edge has very little deformation/chipping and is just slow wear, at most they require one light pass before sharpening and I do it mainly for keeping the edge straight and the visual reference for apex forming.

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